What's the probability of creating a Hello World Program?@Jatt You can have more or less any amount of whitespace between keywords like public, class, etc., so it's somewhat larger, but not significantly so. Though you could try another language — as the joke goes, “I once piped /dev/random into Perl and got a web server”.

Ultrafilters on $\omega$ and lower/upper densityWhile I admit I don't know this subject, I don't see a question here. Do you have to prove that there's an ultrafilter on $ \omega $ such that every $ A \in \mathscr{U} $ has a positive upper density?